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| author |   Christian Brauner <brauner@kernel.org> | 2022-06-21 16:14:53 +0200 |
|---|---|---|
| committer | Christian Brauner (Microsoft) <brauner@kernel.org> | 2022-06-26 18:18:56 +0200 |
| commit | 0e363cf3fa598c69340794da068d4d9cbc869322 (patch) | |
| tree | a1b1b648f6cb3f9b09a41c44b0f3c8c2a3e17422 /security/integrity/evm/evm_main.c | |
| parent | quota: port quota helpers mount ids (diff) | |
| download | linux-dev-0e363cf3fa598c69340794da068d4d9cbc869322.tar.xz linux-dev-0e363cf3fa598c69340794da068d4d9cbc869322.zip | |
security: pass down mount idmapping to setattr hook
Before this change we used to take a shortcut and place the actual
values that would be written to inode->i_{g,u}id into struct iattr. This
had the advantage that we moved idmappings mostly out of the picture
early on but it made reasoning about changes more difficult than it
should be.
The filesystem was never explicitly told that it dealt with an idmapped
mount. The transition to the value that needed to be stored in
inode->i_{g,u}id appeared way too early and increased the probability of
bugs in various codepaths.
We know place the same value in struct iattr no matter if this is an
idmapped mount or not. The vfs will only deal with type safe
vfs{g,u}id_t. This makes it massively safer to perform permission checks
as the type will tell us what checks we need to perform and what helpers
we need to use.
Adapt the security_inode_setattr() helper to pass down the mount's
idmapping to account for that change.
Link: https://lore.kernel.org/r/20220621141454.2914719-8-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Diffstat (limited to 'security/integrity/evm/evm_main.c')
| -rw-r--r-- | security/integrity/evm/evm_main.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index bcde6bc2a2ce..7f4af5b58583 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -755,7 +755,8 @@ void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name) evm_update_evmxattr(dentry, xattr_name, NULL, 0); } -static int evm_attr_change(struct dentry *dentry, struct iattr *attr) +static int evm_attr_change(struct user_namespace *mnt_userns, + struct dentry *dentry, struct iattr *attr) { struct inode *inode = d_backing_inode(dentry); unsigned int ia_valid = attr->ia_valid; @@ -775,7 +776,8 @@ static int evm_attr_change(struct dentry *dentry, struct iattr *attr) * Permit update of file attributes when files have a valid EVM signature, * except in the case of them having an immutable portable signature. */ -int evm_inode_setattr(struct dentry *dentry, struct iattr *attr) +int evm_inode_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, + struct iattr *attr) { unsigned int ia_valid = attr->ia_valid; enum integrity_status evm_status; @@ -801,7 +803,7 @@ int evm_inode_setattr(struct dentry *dentry, struct iattr *attr) return 0; if (evm_status == INTEGRITY_PASS_IMMUTABLE && - !evm_attr_change(dentry, attr)) + !evm_attr_change(mnt_userns, dentry, attr)) return 0; integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry), |